Sweeney-Twin Lake
Hennepin County, MinnesotaMesotrophic
Sweeney-Twin Lake comes in at a B on the grading rubric — a respectable showing for a Minnesota lake of its size and depth. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.
The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Within Hennepin County's 95 graded waters, Sweeney-Twin Lake sits at rank 8, near the top of the local distribution.
No invasive species are currently listed at Sweeney-Twin Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Sweeney-Twin Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-09-06. Grade methodology: LakeGrade methodology.
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Moderate clarity, visible to about 8.2 ft. Phosphorus level: 22 µg/L. Trophic State Index: 48.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.2 ft | C |
| Phosphorus | 22 µg/L | B |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.256 m/yr | 5 |
| Phosphorus | ↑ Improving | -4.1 µg/L/yr | 4 |
Location
County Ranking
Ranked #8 of 95 lakes in Hennepin County
Nearby Lakes in Hennepin County
More Minnesota Lake Rankings
State Parks Near Sweeney-Twin Lake
Other Grade B Lakes in Minnesota
Mesotrophic Lakes in Minnesota
EPA Impairment Status
Sweeney-Twin Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN27-0035-01 · Official waterbody report · Matched by proximity (0.23 km)
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-09-06
Monitoring stations: 2